Double Seat Valve For Separating Media

ABSTRACT

A double seat valve for separating media includes a housing having a first connector for a first pipeline and a second connector for a second pipeline, a first closing member of the first connector and a first closing member seat assigned thereto, the first closing member in closed position cooperating in sealing manner with the first closing member seat via at least one sealing element, a second closing member of the second connector axially spaced from the first closing member, and a second closing member seat assigned to the second closing member, the second closing member in closed position cooperating in sealing manner with the second closing member seat via at least one sealing element. The two closing members can be lifted independently of one another from their respective closing member seats. A leakage space is also provided between the two closing members and discharges into a leakage outlet.

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a continuation of international patent applicationPCT/EP2011/064997, filed on Aug. 31, 2011 and designating the U.S.,which international patent application has been published in Germanlanguage and claims priority from German patent application No. 10 2010046 137.7, filed on Sep. 14, 2010. The entire contents of these priorityapplications are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The invention generally relates to double seat valves used forseparating media. More specifically, the invention relates to a type ofa double seat valve, which comprises a valve housing, which hasconnectors for a first pipeline and a second pipeline, a first closingmember and a first closing member seat assigned thereto, wherein thefirst closing member in its closed position cooperates in a sealingmanner with the first closing member seat via at least one sealingelement, and comprising a second closing member axially spaced from thefirst closing member, and a second closing member seat assigned to saidsecond closing member, wherein the second closing member in its closedposition cooperates in a sealing manner with the second closing memberseat via at least one sealing element, wherein the two closing memberscan be lifted independently of one another from their respective closingmember seat, wherein a leakage space is provided between the two closingmembers and discharges into a leakage outlet.

Double seat valves of the above-mentioned type are used for example inthe food processing industry in product-conveying processing systems.

With double seat valves of this type, there are high requirements on thereliable separation of the media conveyed through the at least twopipelines. The two closing members in their closed position separate thetwo connectors tightly with respect to one another on the inner side ofthe housing, and in the common open position of the two closing membersthe pipelines connected to the two connectors can communicate with oneanother via the housing interior.

A further fundamental requirement of such double seat valves lies in thefact that the closing members, including their closing member seats andthe leakage space located between the closing members, can be thoroughlycleaned.

In order to avoid the need to switch off all processes in a processingsystem, in which such a double seat valve is used, for the purpose ofcleaning the closing members, the closing members seats and the leakagespace, which would reduce the productivity of such a processing system,it is desirable if the cleaning process is carried out for example viaone of the two pipelines, whereas a product process continues in theother pipeline. For this purpose, the two closing members can be liftedindependently of one another from their closing member seat. The term“lift” is to be understood with such double seat valves to mean that oneof the two closing members is moved far enough from its closing memberseat by a short stroke that there is no longer any sealing contactbetween the sealing element of this closing member and the associatedclosing member seat. Here, the other closing member remains in sealedcontact with its closing member seat. A cleaning medium, normally acleaning liquid, can then be fed into the leakage space through thepipeline and the connector to which the lifted closing member isassigned, via the gap between the closing member and the associatedclosing member seat, such that the cleaning medium thoroughly rinses theclosing member seat of the lifted closing member and the sealing elementthereof and the leakage space. The cleaning medium supplied through theconnector associated with the lifted closing member is normally under avery high pressure during this process, which may sometimes be 10 bar ormore.

The cleaning medium runs via the leakage space to the leakage outletand, from here, into the surrounding environment of the double seatvalve.

Document DE 10 2005 057 103 A1 describes the problem that, when feedingthe cleaning medium, no additional overpressure may form in the leakagespace in accordance with the provisions of more recent standards, saidadditional overpressure, in the extreme case, possibly causing the otherclosing member located in the closed position to be moved away from itsclosing member seat, such that cleaning medium could enter the otherpipeline, in which a product process is currently being carried out.

To solve this problem, it is proposed in that document to provide aclosing member with an inclined drainage portion, of which the totalopening cross section is at least approximately as large as the openingcross section of the larger of the two connectors. The problem of anoverpressure build-up in the leakage space as a result of an excessivelylow discharge of cleaning medium from the leakage space during thecleaning process is thus avoided, wherein the leakage outlet has apassage cross section corresponding to the cross section of the leakagespace in order to satisfy this provision.

However, only the problem of avoiding an overpressure in the leakagespace is solved thereby. A further provision of more recent standards isthat, when the leakage space is impinged after lifting of one of the twoclosing members, the at least one sealing element or the closing memberseat of the other closing member, which is located in its closedposition, is not impinged directly by cleaning medium, because cleaningmedium could then also enter the other pipeline, because the cleaningmedium as already mentioned is under a high pressure. With thepreviously mentioned known double seat valve, this provision is notsatisfied. If, for example, the lower closing member of the known doubleseat valve is lifted, and if pressurized cleaning medium is fed into theleakage space in the gap between the closing member and the closingmember seat thereof, the cleaning medium, due to its substantially axialdirection of flow, initially contacts the closing member seat and thesealing element of the upper closing member located in the closedposition, whereby cleaning medium could flow past the sealing element ofthe upper closing member and infiltrate the valve housing region,through which a product medium currently flows.

The above-mentioned problem is overcome in the case of the double seatvalve known from document DE 10 2007 038 124 A1, by a flow barrierelement, which, when one closing member is lifted and as the leakagespace is impinged by cleaning medium, shadows the at least one sealingelement and/or the closing member seat of the other closing member,which is located in its closed position, against direct impingement bythe cleaning medium entering the leakage space. The flow barrier elementthus prevents the cleaning medium, as it enters the leakage space, fromdirectly impinging the seal and/or the closing member seat of the otherclosing member located in its closed position.

Various embodiments of the flow barrier element are disclosed in thecited document. In all these embodiments cited in said document of theflow barrier element, it is necessary for the leakage outlet adjoiningthe leakage space to have at least the same cross section as the leakagespace in order to satisfy the provision already mentioned above, inaccordance with which no pressure may build up in the leakage space.However, this has the disadvantage that the leakage outlet pipeadjoining the leakage space has to have an accordingly large diameterand therefore a wall with a large circumference. This leads to a greatermaterial outlay and therefore to greater initial costs of the knowndouble seat valve.

SUMMARY OF THE INVENTION

It is an object of the present invention to develop a double seat valveto the extent that the above-mentioned provisions of avoiding anoverpressure build-up in the leakage space as well as the directimpingement of the seal and/or of the closing member seat of the closingmember located in its closed position when the other closing member islifted, with simultaneous cost saving can be satisfied.

According to an aspect, a double seat valve for separating media isprovided, comprising a valve housing having connectors for a firstpipeline and a second pipeline; a first closing member, a first closingmember seat, and at least one first sealing element; a second closingmember axially spaced from the first closing member, a second closingmember seat axially spaced from the first closing member seat, and atleast one second sealing element; the first and second closing membersbeing able to be lifted independently of one another from the first andsecond closing member seats, a leakage space arranged between the firstand second closing members and discharging into a leakage outlet; a flowbarrier element arranged between the first and second closing membersfor shadowing, when the first closing member is lifted, at least one ofthe second sealing element and the second closing member seat againstdirect impingement by a medium fed into the leakage space, and forshadowing, when the second closing member is lifted, at least one of thefirst sealing element and the first closing member seat against directimpingement by a medium fed into the leakage space; the flow barrierelement having an annular body, which divides, when one of the first andsecond closing members is lifted, together with said one of the firstand second closing members the leakage space into a first leakage spaceportion and a second leakage space portion, the annular body beingconfigured for a passage of medium through the annular body from thefirst leakage space portion into the second leakage space portion suchthat a second pressure in the second leakage space portion is reducedcompared to a first pressure in the first leakage space portion, themedium reaching the leakage outlet from the second leakage spaceportion.

The double seat valve according to the invention satisfies both theprovision of avoiding direct impingement of the seal and/or of theclosing member seat of the closing member located in its closed positionwhen the other closing member is lifted and also of avoiding anoverpressure build-up in the leakage space as a result of a developmentof the flow barrier element. This is implemented with the double seatvalve according to the invention in that the annular body, in the liftedposition of one of the two closing members, together with that closingmember divides the leakage space into a first leakage space portion anda second leakage space portion, which communicate with one another insuch a way that medium can pass through the annular body from the firstleakage space portion into the second leakage space portion with a dropin pressure. The medium can then flow substantially with no pressure tothe leakage outlet. The closing member located in its closed position islocated here in the second leakage space portion and is thus protectedcompletely against a passing of cleaning medium past its seal and intothe product-conveying valve housing.

With the double seat valve according to the invention, the flow barrierelement thus has two functions in order to satisfy the twoabove-mentioned provisions. When one closing member is lifted, thecleaning medium enters the first leakage space portion at high pressureand then reaches the inner leakage space portion with a reduction ofpressure and a reduction of flow rate, from where it reaches the leakageoutlet. This then has the significant advantage that the leakage outletonly requires a much smaller cross section than the cross section of theleakage space itself. The leakage outlet pipe can thus be formed with amuch smaller diameter, which saves material and therefore initial costs.

So that the medium can pass through the annular body, the annular bodyof the flow barrier element of the double seat valve according to theinvention has passage regions, which preferably give the medium adirection of flow that, where possible, points directly in the directionof the leakage outlet. Here, the passage regions cause a throttling ofthe medium.

In a preferred refinement, when medium passes from the first leakagespace portion, the pressure in the second leakage space portion reducessubstantially to atmospheric pressure at the leakage outlet or even to apressure below the atmospheric pressure.

The provision of avoiding an overpressure in the leakage space issatisfied most efficiently in this embodiment.

In a further preferred refinement, the annular body of the flow barrierelement has a radially extending annular body portion and an adjoiningaxially extending annular body portion, wherein, when one of the closingmembers is lifted and the first leakage space portion is impinged bymedium, the axial annular body portion contacts said closing member in asealing manner.

In this refinement, the annular body of the flow barrier element is atleast L-shaped, but preferably T-shaped, in section parallel to thelongitudinal direction of the double seat valve, since an axiallyextending annular body portion extends away from the radial annular bodyportion on either side thereof. The radial annular body portion,together with the axial annular body portion, the lifted closing memberand the leakage space housing wall, forms the first leakage spaceportion such that, in this embodiment, the first leakage space portionis located radially outside the second leakage space portion. Here, theradial annular body portion preferably takes on the function of blockingthe seal or the closing member seat of the closing member located in theclosed position, and the axial annular body portion takes on thefunction of ensuring the flow-through of the medium into the secondleakage space portion.

When one of the closing members is lifted, the axial annular bodyportion preferably only comes into contact with that closing member in asealing manner when the first leakage space portion is impinged bymedium.

This has the advantage that, in the operating state of the double seatvalve, in which both closing members are in their closed position,leakages cannot only pass through the annular body into the secondleakage space portion, but also via the “leak” between the axial annularbody portion and the respective closing member, whereby leakageidentification is also improved with the double seat valve according tothe invention.

In conjunction with the previously mentioned refinement, it is alsopreferable for the axial annular body portion and the closing member tohave edges engaging one another from behind, via which the axial annularbody portion contacts the closing member in a sealing manner.

In this case, the sealing contact between the axial annular body portionand the lifted closing member is ensured in a simple manner when oneclosing member is lifted, and the flow barrier element in this operatingstate is also held or locked on the lifted closing member in apredetermined position relative thereto, such that, when feedingpressurized medium into the first leakage space portion, the flowbarrier element is not pushed away in an undesired manner to such anextent that the sealing contact between the axial annular body portionand the lifted closing member is cancelled.

In a further preferred refinement, the flow barrier element is arrangedloosely between the closing members and axially movably relativethereto.

The axial movability of the flow barrier element relative to the twoclosing members has the advantage that the housing region of the leakagespace, where the flow barrier element is located, is also easilyaccessible for cleaning. The loose arrangement of the flow barrierelement between the closing members means that the flow barrier elementis not rigidly connected to either of the two closing members and, forimproved cleaning, can therefore be moved away axially slightly from itsoriginal position in the closed state of both closing members when apressurized cleaning medium is fed.

In a further preferred refinement, the annular body of the flow barrierelement has a plurality of apertures, through which the medium can passfrom the first leakage space portion into the second leakage spaceportion, wherein the number and/or individual cross section of theapertures is dimensioned such that the pressure in the second leakagespace portion is substantially at atmospheric pressure or therebelowwhen medium passes through the apertures.

In this preferred refinement of the flow barrier element, the annularbody of said flow barrier element has a plurality of apertures aspassage regions. Such apertures in the form of small holes cause astrong acceleration of the medium when said medium passes through, suchthat the medium exiting from the apertures causes a suction effect inthe second leakage space portion in the manner of a water aspirator,whereby a pressure build-up in the second leakage space portion is inany case avoided. On the contrary, with a corresponding configuration ofthe apertures, it is possible to generate a negative pressure in thesecond leakage space portion. Three such apertures can be provided ineach case in the annular body of the flow barrier element, for exampledistributed in the circumferential direction over the longitudinal axisof the double seat valve, more specifically three apertures for thelifting of one of the closing member and the other three apertures forthe lifting of the other closing member. For example, the apertures mayhave an individual diameter from approximately 1 to 5 mm. Such smallapertures have the advantage that, with corresponding orientationthereof, the medium passing through can be given a direction that leadsdirectly into the leakage outlet and thus avoids a spraying of themedium in the leakage space, which may give rise to an impaired drainageof the medium from the leakage space and therefore to a pressurebuild-up.

In a further preferred refinement, the leakage space is connected to theleakage outlet via one or more drainage openings in one of the twoclosing members, and the apertures in the annular body are aligned withthe one or more drainage openings.

In this case, it is advantageous for the medium passing through theapertures to be directed directly to the drainage openings. Since themedium has a high flow velocity as it passes through the apertures,contact between the medium jets and wall portions of the housing orother parts is thus avoided, which could lead disadvantageously to aspraying of the medium in the leakage space and therefore possibly to animpingement of the seal and/or of the closing member seat of the closingmember located in the closed position, which is to be avoided.

In addition, the apertures are aligned with one another such that thevirtual extensions of the apertures do not intersect before the drainageopenings, and therefore a meeting of the medium jets passing through theapertures is also avoided, which likewise may lead to a spraying ofmedium in the leakage space.

In a further preferred refinement, the one or more drainage openingswiden toward the leakage space.

In this case, the advantage is achieved that the ends of the drainageopenings on the side of the leakage space do not form baffles, againstwhich the medium jets passing through the apertures contactperpendicularly. Rather, a particularly streamlined profile of thedrainage openings is created as a result of the shape of the drainageopenings, which is widened on the leakage space side and thereforerounded.

In a further preferred refinement, the flow barrier element is arrangedbetween the closing members in a manner secured against rotation.

This measure is advantageous in particular with the previously mentionedmeasures, in accordance with which the annular body has a plurality ofapertures, which are aligned with one or more drainage openings. Sincethe flow barrier element is secured against rotation, this alignmentbetween the apertures in the annular body and the drainage openings isreliably maintained during operation of the double seat valve.

In a further preferred refinement, the flow barrier element bearsagainst the housing on the housing side via a seal or a sliding element.

Here, a seal has the advantage that the first leakage space portion,with the exception of the desired passage of medium through the annularbody of the flow barrier element, is sealed even at high pressures withrespect to the second leakage space portion. By contrast, a slidingelement in particular in conjunction with the loose arrangement of theflow barrier element between the two closing members has the advantagethat the flow barrier element is slightly axially movable, and the flowbarrier element cannot be axially blocked.

Alternatively to the previously mentioned refinements, it is alsopossible however for the flow barrier element to bear directly againstthe housing without an additional seal or sliding element.

This refinement has the advantage that the flow barrier element can beproduced particularly cost-effectively, because an additional seal or anadditional sliding element is omitted. In this case, the flow barrierelement or the annular body thereof may be provided on the radiallyouter side with a bead or projection that bears against the housing.This embodiment is then suitable in particular when the flow barrierelement is manufactured from a plastics material.

In a further preferred refinement, the annular body of the flow barrierelement is not in contact in a sealing manner with either of the closingmembers in the closed position of both closing members.

This measure has the advantage that the flow barrier element in theclosed position of both closing members does not hinder leakageidentification, that is to say in the event of a leak of at least one ofthe sealing elements of the two closing members, a leakage can bedetected in spite of the presence of the flow barrier element since theleakage can infiltrate the leakage space between the respective closingmember and the flow barrier element, which can then be determined eitherby the exit of the leakage from the leakage outlet or by correspondingdetectors.

In a further preferred refinement, at least the annular body of the flowbarrier element is manufactured from a plastics material, in particularPEEK.

The advantage of this measure lies on the one hand in the fact that theflow barrier element can likewise be produced cost-effectively, and onthe other hand, in conjunction with one of the above-mentionedembodiments, in accordance with which the axial annular body portion andthe closing member have edges that can engage one another from behind,in the fact that a plastics material is advantageous for reasons ofeasier assembly of the double seat valve, since the corresponding edgeof one or both axial annular body portions of the annular body of theflow barrier element can be connected to the respective closing memberby being clicked into place.

Further advantages and features will emerge from the followingdescription and the accompanying drawing.

It goes without saying that the above-mentioned features and thefeatures yet to be explained hereinafter can be used not only in therespective combinations specified, but also in other combinations or inisolation, without departing from the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

An exemplary embodiment of the invention is illustrated in the drawingand will be described in greater detail with reference to said drawing,in which:

FIG. 1 shows a detail of a double seat valve in longitudinal section,wherein the double seat valve is shown in the closed position;

FIG. 2 shows a detail of the double seat valve in FIG. 1 in the regionof its two closing members, enlarged compared to FIG. 1;

FIG. 3 shows a detail of the double seat valve in FIG. 1 in the regionof its closing members, wherein the double seat valve is shown in itsopen position;

FIG. 4 shows a longitudinal sectional view of a flow barrier element ofthe double seat valve in FIG. 1 in isolation;

FIG. 5 shows a perspective illustration of the flow barrier element inFIG. 4;

FIG. 6 shows a perspective illustration of a closing member of thedouble seat valve in FIG. 1 in isolation;

FIG. 7 shows a detail of the double seat valve in FIG. 1 in the regionof its two closing members, wherein one of the two closing members islifted; and

FIG. 8 shows a detail of the double seat valve in FIG. 1 in the regionof its closing members, wherein the other closing member is lifted.

DESCRIPTION OF AN EXEMPLARY EMBODIMENT

A double seat valve, provided with the general reference sign 10, forseparating incompatible media is illustrated in FIG. 1. Further detailsof the double seat valve 10 and its operating principle are illustratedin FIGS. 2 to 8.

The double seat valve 10 is used for example in a food processingsystem.

The double seat valve 10 has a valve housing 12, which has a first valvehousing portion 14 and a second valve housing portion 16. A firstconnector 18 for connecting a first pipeline (not illustrated) to thedouble seat valve 10 is arranged on the first valve housing portion 14,and a second connector 20 for connecting a further pipeline (notillustrated) to the double seat valve 10 is arranged on the second valvehousing portion 16, wherein the connectors 18 and 20 in the exemplaryembodiment shown are arranged offset from one another by 90° withrespect to a longitudinal center axis 22 of the double seat valve 10. Inthe present description, the longitudinal center axis 22 defines theaxial direction of the double seat valve 10 and parts thereof.

Between the first valve housing portion 14 and the second valve housingportion 16, the valve housing 12 has a valve housing portion 24, whichinternally defines a connection opening 26, via which the interiors ofthe valve housing portions 14 and 16 communicate with one another in theopen state of the double seat valve 10, as is illustrated in FIG. 3.

A first closing member 28 and a second closing member 30 are arranged inthe valve housing 12. The first closing member 28 has a sealing element32, which contacts a first closing member seat 34 in a sealing manner inthe closed position of the closing member 28 according to FIGS. 1 and 2,wherein the first closing member seat 34 is arranged at an upper end ofthe connection portion 24 of the valve housing 12. The second closingmember 30 likewise has a sealing element 36, which contacts a secondclosing member seat 38 in a sealing manner when the second closingmember 30 is located in its closed position, as is illustrated in FIGS.1 and 2.

The first closing member 28 is connected to a driving body 40 a, 40 b,wherein the driving body 40 a, 40 b is connected to a control mechanism41 (not illustrated in greater detail and known per se) to axially movethe closing member 28. The second closing member 30 is likewiseconnected to a driving body 42, which is connected to the controlmechanism 41 to axially move the closing member 30.

A leakage space 44, which in the closed state of the double seat valve10 according to FIGS. 1 and 2 is used to enable a drainage of leakagesin the event of a leak of one or both of the sealing elements 32, 36, islocated between the first closing member 28 and the second closingmember 30 in order to detect a leakage state. To this end, the leakagespace 44 is connected to a leakage outlet 46. The leakage outlet 46 isformed by a tubular continuation of the second closing member 30.

As is clear from FIG. 1, the leakage outlet 46 has a passage crosssection 50, which is smaller than a cross section 52 of the connectionopening 26 in the connection portion 24 of the housing 12. The passagecross section 50 is likewise smaller than the cross section of theleakage space 44, which corresponds substantially to the cross section52 of the connection opening 26.

FIG. 1 shows the closing members 28 and 30 in their common closedposition, in which the interior of the valve housing portion 14 issealed off in a hermetically tight manner from the interior of the valvehousing portion 16.

FIG. 3 shows both closing members 28 and 30 in their common openposition, in which the closing members 28 and 30 are moved axiallyupwardly from their respective closing member seat 34, 38 bycorresponding actuation of the control mechanism 41 by means of thedriving bodies 40 a, 40 b and 42, such that the connection opening 26between the valve housing portions 14 and 16 is open. In this case, aproduct medium for example can be transferred from the connector 18 intothe connector 20.

Additionally to the operating states shown in FIG. 1 or 2 and 3, thedouble seat valve 10 additionally has two further operating states,which are referred to as “lifting” of a respective one of the twoclosing members 28 or 30.

The two operating states of lifting are illustrated in FIGS. 7 and 8.

The lifting of the first closing members 28 is shown in FIG. 7, that isto say the first closing member 28 is lifted axially far enough from itsclosing member seat 34 that the sealing element 32 is brought out ofcontact with the closing member seat 34. By contrast, the second closingmember 30 is still located in its closed position, as is shown in FIG.7.

FIG. 8 shows the lifting of the second closing member 30, wherein thesecond closing member 30 in accordance with FIG. 8 is removed axiallydownwardly by a lifting stroke, more specifically exactly until thesealing element 36 is brought out of contact with the associated closingmember seat 38. During lifting of the second closing member 30, thefirst closing member 28 remains in its closed position, as is clear fromFIG. 8.

The lifting of the first closing member 28 in accordance with FIG. 7 isused to feed a cleaning medium into the leakage space 44 through a gap54 between the closing member 28 and the closing member seat 34. Here,the cleaning medium is supplied via the connector 18 and the pipelineconnected thereto. In particular, the sealing element 32 and the closingmember seat 34 and also the interior of the leakage space 44 are cleanedthoroughly by the cleaning medium. Here, the supplied cleaning medium isnormally under a high pressure, which may sometimes be 10 bar or more.

During lifting of the second closing member 30, a pressurized cleaningmedium is supplied via the connector 20 and the pipeline connectedthereto, and is supplied into the leakage space 44 via a gap 56 betweenthe closing member 30 and the closing member seat 38.

In both cases according to FIGS. 7 and 8, it must be ensured that therespective sealing element (sealing element 36 in FIG. 7 and sealingelement 32 in FIG. 8) and/or the associated closing member seat 34 or38, which contact one another in a sealing manner, are not impinged bythe fed cleaning medium in such a way that the cleaning mediuminfiltrates between the sealing element 32 or 36 and associated closingmember seat 34 and 38, which are contacted in a sealing manner, and intothe respective other valve housing portion 14 or 16. It is thus ensuredas a result of the respective valve housing portion 14 or 16, of whichthe associated closing member 28 or 30 is located in its closedposition, that a produce process can proceed without contamination ofthe product medium by the cleaning medium.

Besides the above-mentioned requirement, in accordance with which,during lifting of one closing member 28 or 30, the sealing element 32 or36 and/or the closing member seat 34 or 38 of the other closing member28 or 30 is not impinged directly by cleaning medium, there is a furtherrequirement that the cleaning medium in the leakage space 44 must notcause a pressure build-up, and instead the cleaning medium has to beconveyed away to the leakage outlet 46 with minimal pressure.

Both above-mentioned requirements are ensured with the double seat valve10 by a flow barrier element 58, which is arranged in the leakage space44 between the first closing member 28 and the second closing member 30.

The flow barrier element 58 will be described in greater detail first,with reference to FIGS. 4 and 5.

The flow barrier element 58 has an annular body 60 extending over theentire circumference (with respect to the longitudinal axis 22). Theannular body 60 has a radially extending and radially outer annular bodyportion 62 and a radially inwardly adjoining and axially extendingannular body portion 64 a, 64 b, which each likewise extend over theentire circumference (with respect to the longitudinal axis 22). Theaxial annular body portion 64 a and the axial annular body portion 64 beach have an edge 66 a and 66 b respectively, which extend over theentire circumference and form a protruding annular flange pointingradially outwardly.

A plurality of apertures 68 a, in the exemplary embodiment shown threeapertures distributed over the circumference, are formed in the axialannular body portion 64 a, wherein the apertures 68 a are oriented at anincline with respect to the horizontal.

A plurality of apertures 68 b, in this case three apertures, arelikewise formed in the axial annular body portion 64 b, only one of saidapertures being shown in each of FIGS. 4 and 5, said apertures likewisebeing directed at an incline with respect to the horizontal, but with asmaller incline than the apertures 68 a.

A plurality of fingers 70, in this case three fingers, which extendpointing radially inwardly toward the longitudinal centre axis of theflow barrier element 58, but end before the longitudinal centre axis,extend radially inwardly from the annular body 60. In addition, aninterior 72 of the flow barrier element 58 is open on both sides in theaxial direction.

The flow barrier element 58 is manufactured in one piece on the wholefrom a plastics material, in this case from PEEK.

The installed position of the flow barrier element 58 in the double seatvalve 10 will be described hereinafter with reference inter alia to FIG.2.

The first closing member 28 has a recess 74 a, which extends over theentire circumference with respect to the longitudinal axis 22 and inwhich the axial annular body portion 64 a of the flow barrier element 58engages. Accordingly, the closing member 30 has a recess 74 b, in whichthe axial annular body portion 64 b of the flow barrier element 58engages.

The recess 74 a has a radially outer edge 76 a, which protrudes radiallyinwardly and extends over the entire circumference about thelongitudinal axis 22. The recess 74 b in the closing member 30 likewiseradially outwardly has a radially inwardly protruding edge 76 b, whichextends over the entire circumference about the longitudinal axis 22.

The diameters of the edges 76 a and 76 b are slightly smaller than thediameters of the edges 66 a, 66 b of the flow barrier element 58, andtherefore the edges 66 a, 66 b and the edges 76 a, 76 b engage oneanother from behind. Since the flow barrier element 58 is manufacturedfrom plastics material, the flow barrier element 58 is clicked into thecorresponding recesses 74 a, 74 b during assembly of the double seatvalve 10, and therefore the axial annular body portions 64 a, 64 b aretrapped in the recesses 74 a, 74 b and can only be removed again fromthe closing members 28 and 30 with an application of force. To this end,forces that correspond to a pressure of at least 13 bar are necessary.

The flow barrier element 58 is arranged loosely between the two closingmembers 28 and 30 and axially movably relative thereto. As is clear fromFIG. 2, the axial depth of the recesses 74 a and 74 b is accordinglydimensioned at least as large as the axial extension of the axialannular body portions 64 a and 64 b so that the axial annular bodyportions 64 a and 64 b can move axially in the recesses 74 a and 74 b.

The radial annular body portion 62 of the flow barrier element 58 hassuch a diameter that it bears against the inner wall of the connectionportion 24 of the housing 12. In the exemplary embodiment shown, theradial annular body portion 62 is provided with a radial seal 78, whichbears in a sealing manner against the inner wall of the connectionportion 24 (apart from in the open position according to FIG. 3). Theseal 78 can also be omitted however, wherein the radial annular bodyportion 62 then preferably ends radially outwardly in a bead or asealing lip, and the bead or the sealing lip then bears against theinner wall of the connection portion 24. Furthermore, it is possible toprovide a sliding element instead of a seal at the radially outer edgeof the radial annular body portion 62.

Before discussing further details of the flow barrier element 58, itsinstalled position and its function, the second closing member 30 willfirst be described with reference to FIG. 6.

Centrally with respect to the longitudinal axis 22, the second closingmember 30 has a central portion 80, via which the second closing member30 is assembled on the driving body 42. A plurality of recesses 82 (onlytwo of which can be seen in FIG. 6), in this case three recesses, aredistributed over the circumference on the central portion 80. Theserecesses 82 are used to receive and guide the respective ends 84 of thefingers 70 of the flow barrier element 58. Due to the fact that the ends84 of the fingers 70 are received in the recesses 82, the flow barrierelement 58 is arranged so as to be axially movable between the closingmembers 28 and 30, but secured against rotation in relation to thelongitudinal axis 22.

A plurality of drainage openings 86 (of which only two can be seen inFIG. 6), in this case three drainage openings, are formed in the closingmember 30 about the central portion 80 and transition into the leakageoutlet 46 (see also FIGS. 1 and 2). The drainage openings 86 widentoward the leakage space 44 and are approximately kidney-shaped in crosssection.

In the installed position of the flow barrier element 58 in the doubleseat valve 10, the apertures 68 a in the axial annular body portion 66 aand the apertures 68 b in the axial annular body portion 66 b arealigned with the drainage openings 86 in the closing member 30, as canbest be seen in FIG. 2. More specifically, one of the apertures 68 a andone of the apertures 68 b is in each case aligned with one of thedrainage openings 86.

The function of the flow barrier element 58 will now be describedhereinafter.

In the closed position of the double seat valve 10, in which bothclosing members 28 and 30 are located in their closed position, as isshown in FIGS. 1 and 2, the flow barrier element 58 is located looselybetween the two closing members 28 and 30 approximately in a centralposition, in which the radial annular body portion 62 leaves a gapbetween itself and the closing member 28 and between itself and theclosing member 30. In the event of a leakage with failure of the seal 32and/or of the seal 38, medium between the radial annular body portion 62and the closing member 28 or the closing member 30 can thus reach theleakage space 44, and from there the leakage outlet 46 via the drainageopenings 86, such that leakage detection is possible. Here, the leakagecan enter the leakage space 44 through the apertures 68 a or 68 b, butmay also pass the edges 66 a and/or 66 b via the recesses 74 a and 74 brespectively.

The flow barrier element 58 therefore does not impair the requiredpossibility of leakage detection.

If the double seat valve 10 is transferred into its open position, theclosing member 30 is moved upwardly toward the closing member 28 via theabove-mentioned control mechanism 41, entraining the flow barrierelement 58. Here, the closing member 30 seals with respect to the flowbarrier element 58, for which purpose an axial seal 88 is provided inthe radial annular body portion 62 of the flow barrier element 58. Here,the flow barrier element 58 in turn contacts the closing member 28 in asealing manner, for which purpose a further axial seal 90 is provided inthe closing member 28. In the open position of the double seat valve 10shown in FIG. 3, the leakage space 44 is sealed against the interior ofthe valve housing portion 14, and therefore medium from the interior ofthe valve housing portion 14 can pass into the interior of the valvehousing portion 16.

During lifting of the first closing member 28 in accordance with FIG. 7for the purposes of cleaning the seal 32 and the closing member seat 34as well as the leakage space 44, a pressurized cleaning medium is fedinto the gap 54 between the closing member 28 and the closing memberseat 34 via the interior of the valve housing portion 14.

In this operating state, the annular body 60 of the flow barrier element58, together with the closing member 28, divides the leakage space 44into a first leakage space portion 92 and a second leakage space portion94. The pressurized cleaning medium fed through the gap 54 causes theflow barrier element 58 to be pushed axially in the direction toward thesecond closing member 30 until the edge 66 a of the axial annular bodyportion 64 a and the edge 76 a of the recess 74 a contact one another ina sealing manner, engaging one another from behind. The flow barrierelement 58 is thus locked on the closing member 28. The radial seal 78of the radial annular body portion 62 or, if no such seal is provided,merely the radial annular body portion 62, seal the first leakage spaceportion 92 with respect to a direct impingement of the seal 36 of theclosing member 30 located in the closed position. The flow barrierelement 58 thus ensures a shadowing or the avoidance of a directimpingement of the seal 36 with cleaning medium.

The pressurized cleaning medium enters the apertures 68 a in the axialannular body portion 66 a from the first leakage space portion 94,whereby the cleaning medium in the form of thin jets is directeddirectly into the drainage openings 86. Here, no overpressure builds upin the second leakage space portion 94. By contrast, the second leakagespace portion 94 here is at atmospheric pressure, that is to say at thepressure prevailing at the end of the leakage outlet 46 into thesurrounding environment, normally a pressure of approximately 1010 mbar.The fingers 70 of the flow barrier element 58 are offset with respect tothe apertures 68 a, such that they do not constitute an obstacle for thecleaning medium jets over their path into the drainage openings 86. Thecleaning medium is strongly accelerated in the apertures 68 a, which forexample have a cross section of a few millimeters, for example 1 to 4mm, such that the cleaning medium jets exiting from the apertures 68 aact in the manner of a water aspirator. With measurements of thepressure in the region of the seal 36 of the second closing member 30,it has been found specifically that even a negative pressure, that is tosay a pressure below atmospheric pressure, is present in the secondleakage space portion 94 a. Since the sealing element 38 is located inthe second leakage space portion 94 a, it is located in thepressure-free space.

In any case, the pressure in the second leakage space portion 94 ishighly reduced compared to the pressure in the first leakage spaceportion 92. This allows the passage cross section 50 of the leakageoutlet 46 to be much smaller than the cross section of the leakage space44 itself, even directly after the leakage space 44, whereby the tubularcontinuation 48 of the closing member 30 can be manufactured in amaterial-saving manner with a smaller diameter, as has already beendescribed above at the outset with reference to FIG. 1.

In the reverse case of lifting of the second closing member 30 inaccordance with FIG. 8, the operating principle of the flow barrierelement 58 is analogous. Pressurized cleaning medium is fed through thegap 56 between the second closing member 30 and the second closingmember seat 38 for the purpose of cleaning the seal 36 and the closingmember seat 38. In this case too, the annular body 60 of the flowbarrier element 58 again divides the leakage space 44 into a firstleakage space portion 92 b and a second leakage space portion 94 b,wherein the axial annular body portion 64 b, together with the radialannular body portion 62 and the closing member 30, then delimits thefirst leakage space portion 92 b. Due to the pressurized cleaningmedium, the flow barrier element 58 is then pushed toward the firstclosing member 28, whereby the edge 66 b of the axial annular bodyportion 64 b contacts the edge 76 b of the recess 74 b in a sealingmanner, said edges engaging one another from behind, and the flowbarrier element 58 is locked on the closing member 30. The pressurizedcleaning medium then passes through the apertures 68 b in the axialannular body portion 66 b and passes therefrom into the second leakagespace portion 94 b, and, due to the alignment of the apertures 68 bpointing toward the drainage openings 86, the cleaning medium jets enterthe drainage openings 86 directly. In this case too, the cleaning mediumjets do not experience any obstacles, and the cleaning medium can flowin a pressure-free manner into the leakage outlet 46 via the drainageopenings 86. In accordance with FIG. 8, the sealing element 32 islocated in the second leakage space portion 94 b and therefore in thepressure-free chamber.

Generally, the apertures 68 a, 68 b are dimensioned in cross sectionand/or in their number such that a pressure substantially equal toatmospheric pressure or even a negative pressure below atmosphericpressure prevails in the second leakage space portion 94 a or 94 b whenthe double seat valve 10 according to FIGS. 7 and 8 is subject to acleaning process.

A further improvement of the cleaning capability of the double seatvalve lies in the fact that, in accordance with FIG. 6, a plurality ofrecesses 96 are distributed circumferentially over the outercircumference on a closure part 98 of the second closing member 30.Specifically, the closure part 98 seals circumferentially with respectto a seal 100, and, since the double seat valve 10 is designed such thatthe second closing member 30 is moved axially upwardly in the openposition, the closure part 98 has to be cleanable from the outside. Therecesses 96 are used for this purpose. When lifting the second closingmember 30, the recesses 96 come to rest at the height of the seal 100,whereby the cleaning medium can be conducted away downwardly through therecesses 96, past the seal 100. In the closed state of the closingmember 30, the recesses 96 are located above the seal 100, and thereforethe seal 100 and the closure part 98 are contacted in a sealing manner.The recesses 96 are oriented at a slight incline with respect to thelongitudinal axis 22, whereby the flow of the cleaning medium isimproved and a rinsing and cleaning of the closure part 98 over theentire circumference is ensured.

What is claimed is:
 1. A double seat valve for separating media,comprising a valve housing having connectors for a first pipeline and asecond pipeline, a first closing member, a first closing member seat,and at least one first sealing element, a second closing member axiallyspaced from the first closing member, a second closing member seataxially spaced from the first closing member seat, and at least onesecond sealing element, the first and second closing members being ableto be lifted independently of one another from the first and secondclosing member seats, a leakage space arranged between the first andsecond closing members and discharging into a leakage outlet, a flowbarrier element arranged between the first and second closing membersfor shadowing, when the first closing member is lifted, at least one ofthe second sealing element and the second closing member seat againstdirect impingement by a medium fed into the leakage space, and forshadowing, when the second closing member is lifted, at least one of thefirst sealing element and the first closing member seat against directimpingement by a medium fed into the leakage space, the flow barrierelement having an annular body, which divides, when one of the first andsecond closing members is lifted, together with said one of the firstand second closing members the leakage space into a first leakage spaceportion and a second leakage space portion, the annular body beingconfigured for a passage of medium through the annular body from thefirst leakage space portion into the second leakage space portion suchthat a second pressure in the second leakage space portion is reducedcompared to a first pressure in the first leakage space portion, themedium reaching the leakage outlet from the second leakage spaceportion.
 2. The double seat valve of claim 1, wherein, when mediumpasses from the first leakage space portion into the second leakagespace portion, the second pressure in the second leakage space portionis reduced substantially to atmospheric pressure at the leakage outletor even to a pressure below the atmospheric pressure.
 3. The double seatvalve of claim 1, wherein the annular body has a radially extendingannular body portion and an adjoining axially extending annular bodyportion, wherein, when one of the first and second closing members islifted and the first leakage space portion is impinged by medium, theaxial annular body portion contacts said one of the first and secondclosing members in a sealing manner.
 4. The double seat valve of claim3, wherein the axial annular body portion and said one of the first andsecond closing members have mutual edges engaging one another frombehind such that the axial annular body portion contacts said one of thefirst and second closing members in a sealing manner.
 5. The double seatvalve of claim 1, wherein the flow barrier element is arranged looselybetween the first and second closing members and axially movablyrelative to the first and second closing members.
 6. The double seatvalve of claim 1, wherein the annular body of the flow barrier elementhas a plurality of apertures, through which, when one of the first andsecond closing members is lifted, medium can pass from the first leakagespace portion into the second leakage space portion, wherein at leastone of the number and individual cross sections of the apertures isdimensioned such that the pressure in the second leakage space portionis substantially at atmospheric pressure or below atmospheric pressurewhen medium passes through the apertures.
 7. The double seat valve ofclaim 6, wherein at least one of the first and second closing membershas at least one drainage opening connecting the leakage space to theleakage outlet, and wherein at least one of the apertures in the annularbody of the flow barrier element is aligned with the at least onedrainage opening.
 8. The double seat valve of claim 7, wherein the atleast one drainage opening widens toward the leakage space.
 9. Thedouble seat valve of claim 1, wherein the flow barrier element isarranged between the first and second closing members in a mannersecured against rotation.
 10. The double seat valve of claim 1, whereinthe flow barrier element has a seal for bearing against an interior wallof the housing.
 11. The double seat valve of claim 1, wherein the flowbarrier element has a sliding element for bearing against an interiorwall of the housing.
 12. The double seat valve of claim 1, wherein theflow barrier element bears directly against the housing, without anadditional seal or sliding element.
 13. The double seat valve of claim1, wherein the annular body of the flow barrier element is not insealing contact with either of the first and second closing members in aclosed position of both, the first and second closing members.
 14. Thedouble seat valve of claim 1, wherein the annular body of the flowbarrier element contacts both, the first and second closing members in asealing manner in an open position of both, the first and second closingmembers.
 15. The double seat valve of claim 1, wherein at least theannular body of the flow barrier element is manufactured from a plasticsmaterial.
 16. The double seat valve of claim 1, wherein at least theannular body of the flow barrier element is manufactured from polyetherether ketone (PEEK).